Booms with sequential hydraulic extension



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BOOMS WITH SEQUENTIAL HYDRAULIC EXTENSION Filed Feb. 5, 1965 0 5 Sheets-Sheet 4 MWWKMWM Jan. 24, 1967 w, LADO BOOMS WITH SEQUENTIAL HYDRAULIC EXTENSION 5 Sheets-Sheet 5 Filed Feb. 5, 1965 (Mimi United. States Patent 3,300,060 BOOMS WITH SEQUENTIAL HYDRAULIC EXTENSION William J. Lado, Rome, N.Y., assignor to Pettibone Mulliken Corporation, Chicago, 11]., a corporation of Delaware Filed Feb. 3, 1965, Ser. No. 430,221 6 Claims. (Cl. 212-55) Cranes with hydraulically extended booms have proved to be very advantageous. Three-part booms, in which two parts telescope within the base part of the boom, are obviously desirable inasmuch as they can be extended to considerably greater lengths than can a two-part boom of the same length when fully retracted for traveling along a road or the like. The present invention relates to booms having at least three parts or length sections, two of which telescope within the main section and are hydraulically extended or retracted. This disclosure relating to the operation of such a boom with the desired sequence of operations achieved automatically is offered for public dissemination in the event patent protection is granted.

In telescopic booms having at least three parts, each telescoping part must telescope within the part behind it and hence must be of smaller cross section and somewhat less sturdy in load carrying capacity. The successively smaller cross sections happen to be advantageous in reducing the tipping weight of the structural parts so that a heavier load can be handled within the limits of safety. However, the forward section, of smallest cross section, naturally is not strong enough to support the maximum load which could be carried by the stronger sections into which the forward section telescopes. Accordingly, it is apparent that if a boom is operating with only half of its maximum extension, the forward section should be telescoped within the section next behind it, so that the strength of the more sturdy rearward section will be used in supporting the load. This has been accomplished heretofore by providing separate valves for the extensioncontrol of the successive telescoped parts, so that the operator could, by choice of the correct valve, cause all of the boom extension to be by extension of the rearmost telescoping part until its extension 'was exhausted, another valve then being used for the extension of the more forward part. In retraction, the more forward part could be retracted first by selection of its valve. According to the present invention, a boom of the plurality of the telescoping parts can be operated to extend these parts or retract them in the correct order by operation of a single valve, the selection of which boom section should be moved being automatic.

According to a further feature of the present invention, the selection is made hydraulically, the hydraulic fluid, under pump pressure, being confined by automatic hydraulic valving to the section which is desirably moved first, until its movement has been completed. The valves known as sequence valves are quite suitable for this purpose.

Additional objects and advantages of the invention will be apparent from the following description and from the drawings.

Designation of figures FIGURES 1 and 2 are side views of a crane embodying the present invention, FIG. 1 showing the boom retracted and in a position for road travel. FIG. 2 shows in full lines, the boom with the heavier of its two telescopic sections extended, the dotted lines indicating the further extension by movement of the lighter forward section of the boom.

FIGURES 3A and 3B jointly comprise a side view of the boom and its supporting structure in detail.

FIGURE 4 is a schematic view of the hydraulic system for sequentially extending the boom sections.

FIGURE 5 is a sectional view, generally vertical, taken approximately along the line 55 of FIG. 3B.

FIGURES 6, 7 and 8 are sectional views taken approximately along the lines 66, 77 of FIG. 3A and 88 of FIG. 3B, the sections being generally vertical when the boom is horizontal.

Although the following disclosure offered for public dissemination is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.

General description The three-part boom of the present invention may find its greatest utility in connection with highly mobile cranes which are frequently moved from place to place, often along highways. These may be truck-mounted cranes, or, as seen in FIGS. 1 and 2, self-propelled cranes. In FIG. 1, the boom 11 is fully retracted. It may be of such a length that the transportation of the crane under its own power along highways present no severe problem. FIG. 2 shows the same crane with the boom somewhat elevated and telescopic part 12 extended out of main boom part 13. In this condition, the boom is nearly twice as long as in FIG. 1 and its forward reach beyond the front wheels is considerably more than double that of FIG. 1. For still further reach or height, the boom is made even longer by telescoping its third part 14 as indicated in dotted lines in FIG. 2.

FIG. 2 also shows the boom 11 partially elevated by hydraulic cylinders 16. It may also be recognized from FIGS. 1 and 2 that the boom 11 is pivoted at 17 to a rotating frame 18 carried by a turntable 19 centrally mounted on the chassis 21.

As seen in FIG. 3A, the first telescoping boom section 12 is actuated by a hydraulic cylinder 23, the piston rod 24 of which is pivoted to a bracket 26 carried by the boom section 12. The cylinder 23 is double-acting. When pump pressure is applied to the left of its piston, boom section 12 is extended. When pump pressure is supplied to the right of its piston, boom section 12 is retracted.

As seen in FIG. 3A, boom section 14 is fully telescoped within boom section 12. It is actuated by hydraulic cylinder 27, which is also double-acting, to extend and retract boom section 14. The piston rod 28 of cylinder 27 is pivoted by pin 29 to this forward boom section 14, the cylinder being pivoted by pin 31 to section 12.

It can be seen from FIG. 3A that boom section 15 has an overall cross section substantially less than that of the first telescopic boom section 12. This is possibly even more apparent from FIGS. 6 and 7, which also show that this substantial difference in the overall cross sections is relatively inevitable, the illustrated form providing a relatively minimum clearance.

It is also apparent from FIGS. 3 and 7 that even the stronger first telescopic boom section 12 is substantially less sturdy than the main or base boom section 13.

From these comparative strengths of the respective boom sections, it is apparent that for handling loads of nearly the maximum capacity of the crane, it would be undesirable to have the boom section 12 remain telescoped within the base boom section 13 while the forward boom section 14, the lightest of all, is extended. In other words, it is desirable that the initial extension from the fully collapsed position of FIG. 1 be by movement of the first telescopic boom section 12, section 14 moving with it by virtue of being locked with respect to it by cylinder 27 into which no oil is flowing at this time. Then the forward boom section should be extended and retracted, before retraction of the intermediate boom section.

Hydraulic sequence circuitGeneral description The hydraulic circuit by which the boom sections are extended hydraulically in the proper order and retracted hydraulically in the reverse order, which is also proper for retraction, is shown in FIG. 4.

The crowding and retraction functions are controlled by a single valve 36 which is manually actuated by lever 35 through connecting part 37. As is well understood, the valve 36 can supply a pressure from pump 38 to either of its cylinder lines 39 and 41, simultaneously connecting the other of these two lines to the return line 40 which discharges the hydraulic fluid or oil into tank 43. Valve 36 also has a neutral or hydraulic lock position in which both lines 39 and 41 are closed.

If valve 36 is operated to supply oil to the line 39, which may be called the crowd line, the, oil initially flows, as shown by the arrows "E entering the rear of cylinder 23, the left-hand end as seen in FIG. 4. This extends piston rod 24 and bracket 26 which, as seen in FIG. 3A, is attached to the first telescopic section 12 of the boom, thus extending this section. As this section moves outwardly, crowd cylinder 27 moves with it, this being represented diagrammatically in FIG. 4 by the broken line connection between bracket 26 and cylinder 27.

As the oil enters the rear end of cylinder 23, oil must also flow from the forward end thereof, the flow at this time being indicated by the arrows E. This oil is able to flow freely through the check valve portion 42 of sequence valve 45, back through crowd control valve 36 to the reservoir 43.

It will be observed that the crowd line 39 divides into two portions, 39a and 39b. During the crowding movement of cylinder 23, oil is prevented from following the line 39b by virtue of the fact that it cannot enter cylinder 27 without causing oil to flow from the other end of that cylinder through the conduits indicated by the arrows e, that is, through line 44. Flow through the line 44 is resisted at this point by sequence valve 46. The check valve portion 47 of sequence valve 46 will not permit flow in the direction in question. The relief valve portion 48 will permit flow in that direction but only when a fairly high pressure is reached, the pressure for which the valve may be set by removing cap 49.

When piston rod 24 reaches the end of its stroke, no

more oil can enter crowd cylinder 23. Accordingly, the

full pump pressure from pump 38 is available, and the pressure does in fact rise to a level that is higher than is ordinarily needed to extend piston rod 24. When this oil pressure reaches a sufliciently high pressure, it can force oil through the relief valve 48 doing this by flowing through line 3% into the rear end of crowd cylinder 27, forcing oil from the forward end through line 44, through hose 51, reel 52 and line 53- to sequence valve 46. The oil forced through relief valve 48 passes from sequence valve 46 through line 50, line 41, valve 36 and line 42 to tank 43. Thus, it is only after the piston rod 24 has been fully extended by cylinder rod 23 that the piston rod 28 will normally be extended by cylinder 27.

When the valve 36 is operated in the opposite direction, the pump pressure is supplied to line 41. Line 41 connects with both line 41b and line 41a. However, at the initial stage, flow through line 41b is prevented by sequence valve 45.

The check valve portion 42 does not 4 permit flow in the direction in question, and the relief valve portion 54 will not permit the flow until a pressure is reached for which it is set. Accordingly, the oil flows through line 50, flows freely through check valve 47 through line 53, reel 52, line 51 and line 44 into the forward end of crowd cylinder 27, thereby retracting piston rod 28, oil being discharged from the rear end of cylinder 27 through hose 55, reel 52, line 39b, line 39, valve 36 and return line 40 to tank 43.

Thus, upon retraction, the intial movement is of the forward boom section 14, collapsing into boom section 12 which, at this stage, remains stationary.

When the piston rod 28 reaches the limit of its inward movement, oil can no longer enter cylinder 27, and accordingly, the pressure builds up in line 41 until it can overcome the relief valve 54. At this time, it will flow through line 56 and line 57 to the forward end of cylinder 23, retracting its piston rod 24.

Lines 58 and 59 are merely bleed or vent lines provided for proper operation of sequence valves 45 and 46.

In FIG. 4, reel 52 has been shown in two sections for clarity, but as seen in FIG. 5, there is a single reel. It is provided with a biasing device 60 which causes it to reel the hoses in and allows it to pay them out. The reel includes a hydraulic swivel connection for each of the hoses. To this end there may be one hydraulic swivel connection on each side of the reel or a two-channel hydraulic swivel connection on one side of the reel. The reel 52 must, of course, .be quite large. There is plenty of room for it, however, in rotary pedestal 18. Accordingly, a pulley or sheave 61 is located as seen in FIG. 3B so that as boom section 14 and cylinder 27 move back and forth with boom section 12, the hoses will move longitudinally of the boom quite freely. In FIG. 4, the

pulley 61 has been shown as two pulleys for clarity. The two parts of pulley 61 and the two indications of reel 52 have been joined by a broken line to suggest unity in each case.

Further details It is believed that the invention has been described adequately to enable those skilled in the art to practice the same. Additional details, especially with respect to the boom construction, have been illustrated, and they may also be helpful toanyone practicing the invention. Probably even the uninitiated will recognize that a load hook 71 may be raised and lowered by cable 72 wound on power winch 73, the powering means being not shown. Slide pad or wear shoes 76, 77, 78 and 79 are preferred over rollers at the main load-bearing positions. Main slide pad 77 is preferably rockable. Eccentrically adjustable rollers 81 may also be provided, serving as guide rolls to keep boom section 12 laterally centered.

Settings for the relief valve 48 and the relief valve 54 would depend on various factors including the weights and frictional characteristics of the parts. It may be helpful to know that settings in the region of 500 pounds per square inch have been found satisfactory on some cranes of the 25,000 pound capacity class. The setting should not be over half of the available pump pressure.

Support of crowd cylinders To obtain maximum use of the present invention, it is preferred that the boom sections be quite long and that therefore the successive crowd movements be quite long. This presents a problem in connection with the support of the crowd cylinders. When long cylinders are fully extended, and are supported only at pivotal I points to the rear of the cylinder and forward of the of the main boom 13. There is no such plate available for support of the front end of cylinder 27, this cylinder being surrounded by forward boom section 14 when this boom section is collapsed. However, a roller 88 is carried by the forward boom section and positioned just under the cylinder 27. As the cylinder 27 extends its piston, roller 88 moves with forward section 14. Accordingly, when forward section 14 is fully extended, roller 88 is under the forward end portion of cylinder 27.

Achievement The present invention, especially in the illustrated form, has proved quite satisfactory in providing crowding action in a three-part boom with the proper sequence of movements both in extending the boom and in retracting the boom, in response to the simplest possible movements of a single control valve. This aids in providing exceptionally long telescopic booms. Preferably the angle to which the boom may be elevated is somewhat higher than has been common on telescopic booms heretofore. This not only permits raising the load to a higher level, but also permits raising it to that level from a point close to the machine where the tipping action is best resisted so that maximum loads can be raised to the maximum height permitted by the long boom.

What is herein claimed is:

1. A telescopic boom including a forward telescopic boom section which telescopes within a stronger rearward telescopic boom section, both telescoping within a still stronger main boom; and a hydraulic boom-crowd system including a manually operable control valve, a first hydraulic cylinder means connected between the main boom and the rearward telescopic boom section, a second hydraulic cylinder means connected between the forward boom section and the boom section immediately rearward of it, both hydraulically connected by a hydraulic conduit system to the said valve to be controlled by the valve in one of its positions to extend the cylinder means and their respective boom sections, and by the valve in another of its positions to retract the same; and sequence valve means in said hydraulic conduit system to cause the second hydraulic cylinder means to remain retracted until the first hydraulic means is fully extended, and to cause the first cylinder means to remain extended until the second cylinder means is fully retracted; said sequence valve means automatically confining the flow for said cylinder means to flow to and from the first hydraulic cylinder means, generally except when said first hydraulic cylinder means is fully extended.

2. A telescopic boom including a forward telescopic boom section which telescopes within a stronger rearward telescopic boom section, both telescoping within a still stronger main boom; and a hydraulic boom-crowd system including a manually operable control valve, a first hydraulic cylinder means connected between the main boom and the rearward telescopic boom section, a second hydraulic cylinder means connected between the forward boom section and the boom section immediately rearward of it, both hydraulically connected by a hydraulic conduit system to the said valve to be controlled by the valve in one of its positions to extend the cylinder means and their respective boom sections, and by the valve in another of its positions to retract the same; and sequence valve means in said hydraulic conduit system to cause the second hydraulic cylinder means to remain retracted until the first hydraulic means is fully extended, and to cause the first cylinder means to remain extended until the second cylinder means is fully retracted; said sequence valve means including a directional valve in the conduits leading to each cylinder, that in the conduits for the first cylinder, preventing flow in the boom retracting direction until a predetermined pressure is reached higher than is required to retract the second cylinder, and that in the conduits for the sec- 0nd cylinder preventing flow in the boom extending direction until a predetermined pressure is reached higher than required to extend the first cylinder, both valves permitting free flow in the opposite direction.

3. A telescopic boom including a forward telescopic boom section which telescopes within a stronger rearward telescopic boom section, both telescoping within a still stronger main boom; and a hydraulic boom-crowd system including a manually operable control valve, a first hydraulic cylinder means connected between the main boom and the rearward telescopic boom section, a second hydraulic cylinder means connected between the forward boom section and the boom section immediately rearward of it, both hydraulically connected by a hydraulic conduit system to the said valve to be controlled by the valve in one of its positions to extend the cylinder means and their respective boom sections, and by the valve in another of its positions to retract the same; and sequence valve means in said hydraulic conduit system to cause the second hydraulic cylinder means to remain retracted until the first hydraulic means is fully extended, and to cause the first cylinder means to remain extended until the second cylinder mean-s is fully retracted, one of said cylinder means being within the boom section it moves, and the other being external of the boom section it moves, and support means for the cylinder means when extended including a roller carried by the internally moved boom section moving under and along the cylinder in supporting relationship to the cylinder means as the section moves, and means having a fixed longitudinal position with respect to the externally located cylinder to support it and carried by the member to which the cylinder is connected.

4. A telescopic boom including a forward telescopic boom section which telescopes within a stronger rearward telescopic boom section, both telescoping within a still stronger main boom; and a hydraulic boom-crowd system including a manually operable control valve, a first hydraulic cylinder means connected between the main boom and the rearward telescopic boom section, a second hydraulic cylinder means connected between the forward boom section and the boom section immediately rearward of it, both hydraulically connected by a hydraulic conduit system to the said valve to be controlled by the valve in one of its positions to extend the cylinder means and their respective boom sections, and by the valve in another of its positions to retract the same; and sequence valve means in said hydraulic conduit system to cause the second hydraulic cylinder means to remain retracted until the first hydraulic means is fully extended, and to cause the first cylinder means to remain extended until the second cylinder means is fully retracted, one of said cylinder means being within the boom section it moves, and the other being external of the boom section it moves, and support means for the cylinder means when extended including a support element carried by the internally moved boom section moving under and freely shiftable along the cylinder in supporting relationship to the cylinder means as the section moves, and means having a fixed longitudinal position with respect to the externally located cylinder to support it and carried by the member to which the cylinder is connected.

5. A telescopic boom including a forward telescopic boom section which telescopes within a stronger rear- Ward telescopic boom section, both telescoping within a still stronger main boom; and a hydraulic boom-crowd system including a manually operable control valve, a first hydraulic cylinder mean-s connected between the main boom and the rearward telescopic boom section, a second hydraulic cylinder means connected between the forward boom section and the boom section immediately rearward of it, and hydraulically connected by a hydraulic conduit system to the said valve to be controlled by the valve in one of its positions to extend the cylinder means and their respective boom sections, and by the valve in another of its positions to retract the same; and automatic valve means in said hydraulic conduit system to cause the second hydraulic cylinder means to remain retracted until the first hydraulic means is fully extended, and to cause the first cylinder means to remain extended until the second cylinder means is fully retracted; said automatic valve means automatically confining the flow for said cylinder means to fiow to and from the first hydraulic cylinder means, generally except when said first hydraulic cylinder means is fully extended.

6. A telescopic boom including a forward telescopic boom section which telescopes Within a stronger rearward telescopic boom section, both telescoping within a still stronger main boom; and a hydraulic boom-crowd system including a manually operable control valve, a first hydraulic cylinder means connected between the main boom and the rearward telescopic boom section, a second hydraulic cylinder means connected between the forward boom section and the boom section immediately rearward of it, and hydraulically connected by a hydraulic conduit system to the said valve to be controlled by the valve in one of its positions to extend the cylinder means and their respective boom sections, and by the References Cited by the Examiner UNITED STATES PATENTS 2,877,787 3/1959 Brueder 91412 X 3,171,545 3/1965 Knight et a1. 212144 3,187,905 6/1965 Moskopf et al 21255 3,217,606 11/1965 Bolton et al. 91189 X FOREIGN PATENTS 1,122,682 1/ 1962 Germany.

ANDRES H. NIELSEN, Primary Examiner.

EVON C. BLUNK, Examiner.

A. L. LEVINE, Assistant Examiner. 

1. A TELESCOPIC BOOM INCLUDING A FORWARD TELESCOPIC BOOM SECTION WHICH TELESCOPES WITHIN A STRONGER REARWARD TELESCOPIC BOOM SECTION, BOTH TELESCOPING WITHIN A STILL STRONGER MAIN BOOM; AND A HYDRAULIC BOOM-CROWD SYSTEM INCLUDING A MANUALLY OPERABLE CONTROL VALVE, A FIRST HYDRAULIC CYLINDER MEANS CONNECTED BETWEEN THE MAIN BOOM AND THE REARWARD TELESCOPIC BOOM SECTION, A SECOND HYDRAULIC CYLINDER MEANS CONNECTED BETWEEN THE FORWARD BOOM SECTION AND THE BOOM SECTION IMMEDIATELY REARWARD OF IT, BOTH HYDRAULICALLY CONNECTED BY A HYDRAULIC CONDUIT SYSTEM TO THE SAID VALVE TO BE CONTROLLED BY THE VALVE IN ONE OF ITS POSITIONS TO EXTEND THE CYLINDER MEANS AND THEIR RESPECTIVE BOOM SECTIONS, AND BY THE VALVE IN ANOTHER OF ITS POSITIONS TO RETRACT THE SAME; AND SEQUENCE VALVE MEANS IN SAID HYDRAULIC CONDUIT SYSTEM TO CAUSE THE SECOND HYDRAULIC CYLINDER MEANS TO REMAIN RETRACTED UNTIL THE FIRST HYDRAULIC MEANS IS FULLY EXTENDED, AND TO CAUSE THE FIRST CYLINDER MEANS TO REMAIN EXTENDED UNTIL THE SECOND CYLINDER MEANS IS FULLY RETRACTED; SAID SEQUENCE VALVE MEANS AUTOMATICALLY CONFINING THE FLOW FOR SAID CYLINDER MEANS TO FLOW TO AND FROM THE FIRST HYDRAULIC CYLINDER MEANS, GENERALLY EXCEPT WHEN SAID FIRST HYDRAULIC CYLINDER MEANS IS FULLY EXTENDED. 